Diseases involving inflammation are characterized by the influx of certain cell types and mediators, the presence of which can lead to tissue damage and sometimes death. Diseases involving inflammation are particularly harmful when they afflict the respiratory system, resulting in obstructed breathing, hypxemia, hypercapnia and lung tissue damage. Obstructive diseases of the airways are characterized by airflow limitation (i.e., airflow obstruction or narrowing) due to constriction of airway smooth muscle, edema and hypersecretion of mucous leading to increased work in breathing, dyspnea, hypoxemia and hypercapnia. While the mechanical properties of the lungs during obstructed breathing are shared between different types of obstructive airway disease, the pathophysiology can differ.
A variety of inflammatory agents can provoke airflow limitation including allergens, cold air, exercise, infections and air pollution. In particular, allergens and other agents in allergic or sensitized animals (i.e., antigens and haptens) cause the release of inflammatory mediators that recruit cells involved in inflammation. Such cells include lymphocytes, eosinophils, mast cells, basophils, neutrophils, macrophages, monocytes, fibroblasts and platelets. Inflammation results in airway hyperresponsiveness. A variety of studies have linked the degree, severity and timing of the inflammatory process with the degree of airway hyperresponsiveness. Thus, a common consequence of inflammation is airflow limitation and/or airway hyperresponsiveness.
Currently, therapy for treatment of inflammation predominantly involves the use of glucocorticosteroids. Other anti-inflammatory agents are used including cromolyn and nedocromil. Symptomatic treatment with beta-agonists, anticholinergic agents and methyl xanthines are clinically beneficial for the relief of discomfort but fail to stop the underlying inflammatory processes that cause the disease. The frequently used systemic glucocorticosteroids have numerous side effects, including, but not limited to, weight gain, diabetes, hypertension, osteoporosis, cataracts, atherosclerosis, increased susceptibility to infection, increased lipids and cholesterol, and easy bruising. Aerosolized glucocorticosteroids have fewer side effects but can be less potent and have side effects, such as thrush.
Other anti-inflammatory agents, such as cromolyn and nedocromil are much less potent and have fewer side effects. Anti-inflammatory agents that are primarily used as immunosuppressive agents and anti-cancer agents (i.e., cytoxan, methotrexate and immuran) have also been used to treat inflammation. These agents, however, have serious side effect potential, including, but not limited to, increased susceptibility to infection, liver toxicity, drug-induced lung disease, and bone marrow suppression. Thus, such drugs have found limited clinical use for the treatment of most airway hyperresponsiveness lung diseases.
The use of anti-inflammatory and symptomatic relief reagents is a serious problem because of their side effects or their failure to attack the underlying cause of an inflammatory response. There is a continuing requirement for less harmful and more effective reagents for treating inflammation, Thus, there remains a need for processes using natural (i.e., non-synthetic) reagents with lower side effect profiles and less toxicity than current anti-inflammatory therapies.